Army bomb disposal experts were called to Camberley on Monday morning to deal with a "suspicious" object that turned out to be a radio device... Shortly before 3pm, Surrey Police said the unit had been confirmed to be a "transmitter or repeater for a citizen or pirate band radio station", and that roads had been reopened and cordons lifted.

Of course this piqued the interest of the Wireless Waffle team. Let's look at the possible options:

CB RepeaterSuch things do exist but require a great deal of technical skill to install and operate. As CB radio operates at 27 MHz, they generally require large antennas, and as transmitter powers are usually at least 4 Watts, need power supplies the kind of size that wouldn't easily be left lying around in a piece of woodland.Probability rating: ***** (2 out of 5)

Pirate RepeaterNot something that is often heard of, in fact, do a 'google' search and nothing of any substance comes up. One possibility is that it could have been a PMR446 repeater which, whilst not strictly legal, is not fully pirate as it operates on an unlicensed basis. Such devices would (sensibly) be located on high ground, though they could be operated from batteries for some time. Ideally, they would be high off the ground too (the news report does not indicate whether the so-called repeater was on the floor or up a tree).Probability rating: ***** (1 out of 5)

FM Pirate TransmitterMost FM pirate stations in the UK use transmitters on top of tower-blocks. The area in question is clearly not one bedecked with such skyscrapers, it is woodland. It is not unheard of for pirates to put transmitters up trees but there are better places, especially those with power and somewhere dry to put the transmitter. There aren't that many pirates in this area, Point Blank FM was one which used to broadcast specifically to the area but it hasn't been on air in that part of the world for many months. Pressure FM (also known as 'Presha') is another station in that part of the world. It is possible they would use a site such as that, but if they were locals, presumably they would know the area was largely military and steer clear of it?Probability rating: ***** (4 out of 5)

Short-Wave Pirate TransmitterShort-wave pirates are almost uniquely confined to woodlands in order to string up the large antennas necessary given the frequencies they use. They often use hidden battery powered equipment. On the face of it then, this is exactly the kind of place you would expect to find such a transmitter. The bigger question is whether any such pirates operate from that part of the country, the answer to which is, of course, 'who knows?' Certainly there is some history in the area including Radio Fax which used to operate from Surrey in the late 1980s, and of course, the infamous Radio Jackie which used to operate from the London end of Surrey. There's also a vague recollection of a maildrop for short-wave pirates that was in that part of the world (though my memory is a bit hazy on that). Anyhow, it's not impossible but the number of UK-based short-wave pirates seems very much in decline.Probability rating: **** (3 out of 5)

Our conclusion then - probably an FM pirate - but a bit of a stupid one to go so near to ministry of defence land!

Wireless Waffle has talked extensively about pirate radio in the past, from short-wave music stations, to Brazilian sat-jackers. But it seems that, of all the nations on the planet, the Russians hold the baton for being the biggest pirates of them all.

This story begins when reading the latest intruder report from the IARU Region 1 Monitoring System. The report indicated that there had been an intrusion into the 80 metre amateur band between 3.5 and 3.6 MHz by Russian pirate stations running AM. Now historically the Voice of Korea (the North Korean broadcaster) has been transmitting in the 80 metre band (or the 75 metre band as it's called in in North America) on 3560 kHz in AM and the immediate assumption was that these new signals couldn't possibly be Russian pirates, but must be the Voice of Korea and perhaps a few other stations trying to jam it. The IARU report, however, says that the carriers are very unstable and that the modulation is voices in Russian.

So the only thing to do to verify this story is to turn on a receiver and have a listen. Having done this, there were no obvious signals in the 80 metre amateur band. Having previous heard pirates just below the band at around 3450 kHz, the tuning dial was slowly rotated to ever lower frequencies. Nothing. And then, at 3175 kHz, something. A weak carrier... no, two carriers alternating... both rather unstable in frequency. Switching the receiver to AM yielded weak modulation. A bit more tuning, to 3125 kHz and a much stronger AM signal with a Russian voice and a wobbly carrier. Hey presto!

But what are these odd signals? Are they military operators in a private net (if so, why AM and why unencrypted)? Are they some kind of harmonics or intermodulation? Googling didn't bring much until a page on Sparky's Web Blog was found. It seems that these are effectively the equivalent of Russian CBers but presumably using much lower frequencies given the large distances between Russian cities. The band is known as the тройка band ('troika' in English which has several meanings from 'three of a kind' to a sledge or fairground ride). The band runs from approximately 2900 to 3200 kHz which are internationally allocated to the Aeronautical Mobile and Mobile services.

There are aeronautical frequency assignments in the band (2872, 2899, 2921, 2962 and 3016 are frequencies assigned to North Atlantic traffic for example), but these lower frequencies are less often used unless propagation makes it totally necessary. Oddly, the various frequency lists for the band show very little aeronautical use in Russia (other than Irkutsk on 3016 kHz) - a coincidence? Probably the pirates know this and therefore feel free to mess about in the aviation bands, knowing that the Russian authorities are likely to be little interested in their activities.

If you're in Europe, when it gets dark (and lower frequency propagation opens up over the continent), why not give them a listen. It's fun to chase the carriers up and down in frequency. If you speak Russian, perhaps you could provide some translation as to what on earth they are talking about!

P.S. You might also want to take a listen to 2920 kHz USB as this seems to be a common calling channel for the more technically adept Russian pirates.

Around the short-wave world, mention of 'PsyOps' has recently had reason to reappear. It refers to psychological warfare being conducted by NATO forces to 'scare' Colonel Gadaffi's forces into remission through a variety of activities. One of these activities is the broadcast of semi-threatening, warning messages to troops loyal to Libya's erstwhile leader.

These messages have apparently been broadcast from a Lockheed Martin EC-130 aircraft known as Commander Solo overflying the region and are using the frequencies which belong to the 'Great Man Made River Authority' (GMMRA) which is Libya's authority responsible for artificially transporting water from wells in the Sahara desert via a big pipe to population centres in the North. Why NATO would have chosen these frequencies is not known, however there is (or was) apparently an ALE network on these channels that was presumably in regular use and hence there would be several receivers across the country in 'important offices' which would hear the PsyOps transmissions.

Of the above, NATO PsyOps transmissions have so far been heard on: 6877, 9376, 10125, 10404 kHz. Note that the 10125 kHz frequency is slap bang in the middle of the 30 metre amateur band but as this is a shared frequency with other services the transmission by the military does not contravene the ITU frequency allocation tables and is therefore, effectively legal. The use of 7000 kHz by the GMMRA is not, however, legal as this is an exclusive amateur allocation. Initially, many of the PsyOps transmissions were jammed (presumably by the Gadaffi regime) however they no longer appear to be so.

Here's the Wireless Waffle recording of Commander Solo on 10404 kHz made at 14:00 GMT on 12 July 2011. The transmission ceased at 14:20 GMT. The noise underneath the transmission also ceased around the same time, however whether the two are connected (ie the noise is an attempt at jamming) can not be confirmed. Given that this recording was made in the UK, it is clear that the power of the transmitter used by Commander Solo and his ilk must be reasonbly high. Judging by the signal strength and general propagation conditions at the time of the recording, a radiated power of at least 1 kiloWatt would seem about right. As normal HF aircraft radios have powers of at least 200 Watts, this seems quite feasible.

Of course, all that the Colonel has to do to stop the NATO transmissions becoming a nuisance, is hand out free power line adaptors to at least one house on every street and all short-wave frequencies would be instantly jammed. Perhaps Colonel Gadaffi is an investor the Comtrend PLT devices that do all the damage and the reluctance of Ofcom to do anything about them is part of some previous UK-Libya trade agreement on arms sales. Surely now that the UK is part of a force against Gadaffi, Ofcom can now breach the terms of this agreement with the Libyan government to pollute short-wave and finally get rid of the menace of PLT?

Tuning around the 13 MHz broadcast band, Radio Nederland on 13700 kHz being transmitted from Wertachtal in Germany was sounding rather odd. It had a very pronounced echo which made understanding it very difficult (if you could understand Dutch in the first place!)

You will note in the brief recording that towards the end the echo becomes less evident and listening over a longer period it was clear that the echo faded in and out. This can only mean one of two possible things:

(1) The echo was being caused by transmitting the same material, slightly delayed, from a second transmitter site; or(2) The echo was being caused by receiving duplicated copies of the same material, delayed by some other means.

As far as was apparent, there were no other transmitters being used on that frequency by Radio Nederland, though there was meant to be a transmitter in China on the same frequency which might have been erroneously relaying the programme by mistake. But the cause is more likely to be some other means. Could it, for example, have been caused by being propagated all the way around the Earth.

A quick calculation shows that the delay associated with a round the globe trip is approximately 133 ms (40000 km at 300000 km/s). A snapshot of the pips on the hour is shown on the right, indicating a delay of about 80 ms - so it can't be that! Even if one signal were short-path and the other long-path the delay would only be slightly shorter at around 127 ms so it's not that either.

No other signals in the band were exhibiting the same characteristics which is usually a good sign that it's not a propagation issue (though the BBC Russian transmission on 13745 kHz from the UK did have some very odd rapid fading on it).

The most likely cause seems to be that there were two transmitters on-air at the same time on the same frequency with the same material. Of the other Radio Nederland transmissions due to be on at the same time, all were present and correct which would suggest that it wasn't a transmitter erroneously on the wrong frequency.